Dear List members I've been looking inside the XScreenSaver package to understand some specifics about X11 stuff and I stumbled upon pretty big performance problem in port where the author himself acknowledges he is currently unaware what to do. The author replaced XCopyArea with something like this If source is 'WINDOW' // get the bits (desired sub-rectangle) out of the NSView via Cocoa. // NSBitmapImageRep *bm = [NSBitmapImageRep alloc]; [bm initWithFocusedViewRect:nsfrom]; unsigned char *data = [bm bitmapData]; int bps = [bm bitsPerSample]; int bpp = [bm bitsPerPixel]; int bpl = [bm bytesPerRow]; releaseme = bm; Then CGDataProviderCreateWithData(.. data .. ) CGImageCreate CGContextDrawImage It's quite an overkill - check http://jwz.livejournal.com/628118.html for more information. So the question is - what to do in order to move bits faster in window backing store or whatever i.e. get as close to the real buffer as possible. Lots of stuff hint as libXPlugin as a source of 'acceleration' for X Server. Is there any way to get a public API for it as well as documentation. May be there is some info on CGBlt_copyBytes function in CoreGraphics as well? I am also quite at a loss - I looked at SDL code - they use QuickDraw to get access to video buffer content, yet QuickDraw is deprecated.. So what's the fastest possible memory to draw to window, access and modify it's internal backing store? Best regards, Stauff__